Ionizing radiation is any electromagnetic radiation with sufficient energy to free an electron from a molecule or an atom. Electronic devices may absorb ionizing radiation under a variety of conditions and circumstances. Electronic devices that are routinely elevated to high altitudes, such as electronic circuitry found in airplanes, rockets, missiles, space vehicles, and the like, are exposed to relatively high levels of ionizing radiation due to the thinner atmosphere at higher altitudes. On the ground, electronic devices may be analyzed for security purposes by equipment that emit X-rays, such as may be done at an import port or an airport, to ensure that undesirable materials are not surreptitiously being brought into a country or carried on an airliner, in a CONEX or an ISO container, or in a semi-trailer. Electronic devices may even be exposed to X-rays by individuals attempting to determine the contents of a container for purposes of theft.
Any electronic device may be negatively impacted after being exposed to a sufficient amount of ionizing radiation. Exposure to ionizing radiation can result in a variety of problems, including memory soft errors, such as a value of one or zero being temporarily changed, complementary metal-oxide semiconductor latchups, frequency changes of oscillators, which can in turn lead to timing issues, shifts in mean output voltage of low-dropout regulators, and the like.
Unfortunately, most radiation detectors capable of detecting ionizing radiation must be powered in order to do so. However, electronic devices are often unpowered, such as in the situations described above, during the periods of time the electronic devices are exposed to such ionizing radiation. Consequently, such electronic devices may unknowingly be powered up after suffering damage from ionizing radiation, and be expected to operate, and instead fail to operate, or fail to operate properly. In some electronic devices, like the electronics on a missile guidance system, failure to operate can be catastrophic.
Those electronic devices that are capable of detecting ionizing radiation in an unpowered state have substantial disadvantages. For example, dye-based dosimeters are relatively inexpensive but are incapable of being queried electronically, and metal oxide semiconductor field effect transitor-based dosimeters are prohibitively expensive and not readily available as a commercial off-the-shelf product.